Chapter 12-3: Numbers
Rules governing how numbers should be expressed in different types of texts can vary wildly from one category to another. Check with your instructor to confirm which system works best for your specific scenario.
Suffixes on Ordinal Numerals
Have you ever seen a number with letters following it? It's an ordinal number. Numbers that do not have these suffixes are called cardinal or arabic numbers).
The suffixes that follow these numbers are -st, -nd, -rd, -th, depending on the number: 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th, 14th, 15th, 16th, 17th, 18th, 19th, 20th, 21st, 22nd, 23rd, 24th, 25th, 101st, 102nd, 103rd, 104th, 105th, 477th, etc.
Overarching Principles When Choosing Between Numerals or Spelling Numbers
Use your number format consistently within the same document.
Choose whichever option is more easily readable by your readership.
That being said, this page will cover generally accepted methods of expressing numbers in texts.
Numbers in Business, Scientific & Technical Papers
Authors that use numbers within advertising, charts, financial documents, graphs, measurements, news reports, statistics, and technical journals usually do not write the numbers in full. Instead, they will use the numeral form (e.g. "1, 2, 3") of the number:
Otherwise, it is useful to know that only numbers less than ten should be written out in full, except when fractions or decimals are involved in business and technical papers.
Rules for Numbers in Academic and Non-Technical Writing
1. Write out numbers that can be stated in one or two words in full:
2. Conversely, use numerals for numbers containing more than two words:
3. Always write out the number in full if it starts the sentence. Avoid using numbers that require more than two words. For those situations, use words such as about, approximately, exactly, precisely, etc.:
4. Fractions should be written out in full, with hyphens:
5. Use a numeral before million, billion, trillion, quadrillion for ease of reading:
6. Use numerals for addresses, dates, degrees, divisions in a book, measurements, pages, prices, percentages, and times. Use either "$" or "dollars" when expressing prices where that currency is appropriate to use. If you use a large quantity of numbers in a text, do not alternate between one format (spelling out in full) and another format (using just the numerals). Instead, use the same format throughout. In the example below, you can see that the number "3" should normally be spelled out; however, the author uses the numeral instead because of the other numbers in the same sentence.
How to Format Long Numerals
This section deals strictly with the format of numerals. That is, "123" and not "one two three."
The format for large numbers is a subject of much debate. However, as an English as a Second Language learner, the following table should help you out with "generally acceptable" formats. Some instructors may have specific guidelines that they wish you to follow and so you should always check with them.
Finally, Anglophone Canadians are generally encouraged to use the so-called Metric formatting; that is, the use of a space instead of a comma to separate groups of three numerals.